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I am building a wall with rebar, cinder blocks, and rebar, as I've seen in many YouTube videos.

 ________||_ ___________ ___________ _____
|        || |           |           |     | <--cinder blocks
|________||_|___________|___________|_____|
|     |  ||       |           |           |
|_____|__||_______|___________|___________|````````````` <-- ground
         ||
         || <-- rebar
         ||

The rebar should stop horizontal movement, as part of the wall acts as a retaining wall.

I heard some people warn if I run the rebar into the ground, it will rust and become useless. How can I stop this from happening?

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  • How long do you need it to last? I put rebar stakes into the ground 20+ years ago to hold down driveway edging timbers. I've had to replace the timbers, but just reused the rebar. If you're that worried, I believe they sell epoxy coated rebar to help prevent rust.
    – FreeMan
    Commented Mar 1, 2021 at 17:29
  • If it will last 20 years, that is great! I was told the rebar would rust right away and be useless.
    – Village
    Commented Mar 1, 2021 at 17:42
  • It depends on where you are located. I live near the Pacific Ocean and it wouldn’t last 2 years.
    – Lee Sam
    Commented Mar 1, 2021 at 18:11
  • I'm in Indiana. I've had no problems.
    – FreeMan
    Commented Mar 1, 2021 at 18:27
  • How high is the wall and how high is the backfill? You might be able to eliminate the rebar stuck in the ground if the wall and backfill is not too high.
    – Lee Sam
    Commented Mar 2, 2021 at 5:50

5 Answers 5

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In some countries rebars are meant to rust in order to get a very durable protection by passivation. The outer thin rust layer of some 1/100 mm protects the inner steel from rust.

This is why on construction sites, these rebars are frequently seen laying unprotected and uncovered for many days before they are used.

In addition, concrete has a basic rather than acidic chemical characteristic, which protects the rebars.

Soil could be a different chemical challenge for rebars, so concrete is a good method to avoid direct contact, as mentioned by others.

In contrast to common believe - and in contrast to the experience with the most expensive throw- away product nowadays, cars - rust can be a very good protection coating. The famous iron pillar in Delhi/India was made some 1600 years ago, stood probably most of these years outdoor in the humid Indian open air without any cover and - as it seems - won't be destroyed by rust in the next centuries to come.

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  • The low humidity and oil on the hands of people touching it are given credit for the pillars minimal deterioration.
    – blacksmith37
    Commented Mar 1, 2021 at 19:44
  • @blacksmith37 Very unlikely. 1.The upper part in 4 m height and above is as protected as the lower parts that can be reached by hand. 2. The inscription parts are also protected - no finger or skin can reach into the thin grooves of the symbols as easy as to the surrounding surface. But rain water and humid air can. 3. There is a scientific description for the protective effect that mentions phosphor from some kind of trees used in the furnace and complex chemical processes - but does not mention any human skin related effect.
    – xeeka
    Commented Mar 1, 2021 at 20:00
  • "low humidity"? According this site, weather-and-climate.com/…, the humidity is over 60% for 3 or more months per year.
    – xeeka
    Commented Mar 1, 2021 at 20:06
  • I read about it about 20 years ago in the ASM International journal . They have changed the journal name so I can't search it. The paper discussed the ancient wrought iron pillar had (relatively) high phosphorus and that oil was applied as an offering in some periods. Weathering steels have added small amounts of P ( and Cu and Cr ) so the P has helped. The important point is that a metallurgical evaluation of the pillar was made roughly 20 years ago and its condition explained technically.
    – blacksmith37
    Commented Mar 2, 2021 at 0:44
  • @blacksmith37 In this abstract there is no mentioning of any hand/skin effect or oil applied to the pillar: sciencedirect.com/science/article/abs/pii/S0010938X00000469
    – xeeka
    Commented Mar 2, 2021 at 12:59
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Bore a 4" hole and pour it full of concrete, so the rebar has 2" concrete cover.

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  • This is what we do using an auger and it works well.
    – nelsonic
    Commented Aug 28 at 19:16
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Bury the blocks far enough into the ground so the rebar isn't doing most of the work. Or, use corrosion resistant rebar.

https://handymansworld.net/types-of-rebar/

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  • Even if the rebar "isn't doing most of the work", that doesn't prevent it from rusting. I do agree, however, with making sure the block goes below grade for a good footing.
    – FreeMan
    Commented Mar 1, 2021 at 18:27
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For rebar applications near sea coasts where corrosion is a problem ; coatings like fusion bonded epoxies are used. Also , more costly ,stainless rebar. If you are in a coastal location in certain parts of the world ,these products may be available.

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  • 1
    Like everything, there’s good, better, and best. Silverware rusts in the drawer in our house because were so near the ocean. The local electric utility won’t allow the meter box to be anything other than 316 stainless, because the box will rust out after a few years with 303 or 304 stainless.
    – Lee Sam
    Commented Mar 2, 2021 at 2:40
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Im using rebar to anchor railroad tie retaining walls and will coat them with Krylon rust preventative enamel paint before driving them into predrilled holes, then put roofing tar over tops of holes after driving rebar 1/4 inch below surface.

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